Display panel or portion thereof with a graphical user interface



FIG. 1 is a front view of a display panel or portion thereof with a graphical user interface showing our new design;

FIG. 2 is a front view of a second embodiment thereof;

FIG. 3 is a front view of a third embodiment thereof; and,

FIG. 4 is a front view of a fourth embodiment thereof.

The outermost broken lines illustrate showing of a display panel or portion thereof and form no part of the claimed design. The remaining broken lines illustrate portions of the graphical user interface and form no part of the claimed design. 

CLAIM The ornamental design for a display panel or portion thereof with a graphical user interface, as shown and described. 